must haves in order to spray paint a hull

[Oliver_ribfan]

Like many of us RIB enthusiasts I am sometimes toying with the idea of spray painting the hull of my RIB.

No experience unfortunately on my side .

I have seen videos about it and beautiful results. My workshed arsenal includes already diverse types sanders and a polishing machine but neither a compressor nor other related paint job tools.

What is the minimum requirement talking about a suitable compressor and a spray gun and other related equipment?

Thanks in advance

[spartacus]

Why the sudden inclination to paint the hull? Is this for purely cosmetic reasons, for example, its been previously antifouled, damage repair cover up? The gel coat that's already on the hull can be refurbished, but its not for the faint heared, sanding through various grits, then polishing with a cutting compound. I'm assuming its a white hull, but maybe not if you're considering painting it?

[Oliver_ribfan]

I felt inspired by beamishken's response in Kevin's neighbor thread about the refurbishment of his 7m RIB. I would like to finally learn how to spray paint and what is needed in terms of machinery.

Originally Posted by beamishken

...
As for the hull I like to use a 2 pack polyurethane car or truck paint, I ran a bodyshop for 20+ years & still occasionally do some paintwork & have painted many boats with good results, the advantage of polyurethane over epoxy or the dedicated boat paints like international perfection is you can sand & polish any imperfections like runs or dirt inclusions & respray & blend in small areas if needed.
...

The hull of my Searider is Tangerine Orange . It is tight and robust but looks a bit patchy. No antifouling. One can see that I have done several repairs to it.
It does not have to look shiny like a mirror as I still consider its workboat roots. As it was sitting on an ERRV the one side looks fresh and the other sunny side looks a bit faded out.

[spartacus]

It's worth looking at Harry Dwyers video when they refurbished his SR4 at Cockwells. Whatever you decide to do, whether painting gelcoat, or spraying, it's all in the preparation, and with gelcoat, the sanding and polishing. Having a big open area to work in, under cover, and potententially being able to work on the hull with the RIB turned over.

[Peter_C]

Today, at least in the USA, we use HVLP paint guns. These use a LOT of air volume, which requires a large air compressor. You also need to keep the air cool and dry, which go together. I would say a minimum sized compressor needs to be around 40 gallons. A cooler coming out of the compressor pump with a water drop filter prior to going into the tank helps tremendously, as does a Motorgard type air filter.

Painting is not hard but does require some setup for the gun, and learning a few techniques.

The cost is going to be more prohibitive. You will spend a minimum of a $1,000 Euros for a cheap setup, and it goes up from there. I have more than that invested in just the painting equipment, but I have seen the cheesy Chinese paint guns produce decent paint jobs.

Climate must be controlled and many of today's paints need to be baked at a high temperature to cure using infrared type lights.

Paint is not as tough as gel coat too which may or may not matter to you. Spartacus shows a great video of how to get a decent gel coat job without expensive tools.

[Max...]

IMHO after many years of trying painting - anything other than basic stuff - just leave it to the pros - especially if we're talking important cosmetics or anything that can be powder coated. This is coming from a real Heath Robinson lover and one who will try and make anything so not being defeatist but if you're painting a hull then....hmmm.

[Oliver_ribfan]

40 gallons correspond with something like 150l. As far as I know the challenge is that the compressor has to be able to deliver constant pressure. Maybe that's where the value is.
1000€ is a good number to calculate with and yeah it's a lot. Thanks very much for the estimate!

In regards to the climate I saw diy-ers using a party tent. But good to mention that there are conditions to meet. That reminds me when I rolled my deck. Temperature and humidity plays a role, definitely.

As a searider fan I know the videos from Harry at Cockwell. Always good and exciting to watch! Cockwell applies the gelcoat with a brush and later sanding / polishing. The result is amazing. So in terms of costs it might be smart to invest the money in good brushes .

[Orwell boy]

Check out posts on here by Nugent ,he was a master of spraying hulls ,very informative and helpful

[kevinsc]

Originally Posted by Orwell boy

Check out posts on here by Nugent ,he was a master of spraying hulls ,very informative and helpful

When you say was a master has he stopped spraying hulls.
I have read his guide on prepping and spraying hulls very good and full of information, and as I'm doing my restoration and most of the stuff I will give it a bash and see what happens.
Cheers Kevin

[Orwell boy]

Sorry ,no I have no knowledge of his current status ,purely just a memory of posts that were very hot on that topic ,maybe there's others on here who can update ?

[beamishken]

Its not about the size of the tank its the output of the pump that is realy critical you need 14/15 cfm driven by 3hp motor. a larger tank of 150l -200l will help smooth out peak demand but any less than 3hp & it won't cope. I use devilbis guns a jga suction gun for primers & a Gti gravity feed hvlp for topcoat & laquer. There are some good cheap copies available for beginners The key is good prep, sprayed paint will show up every imperfection in the preparation. I re gelcoated an sr4 hull a few years ago & applying the gelcoat is the easy bit, sanding & polishing to a good finish afterwards is a nightmare. I vowed id never do it again. Sanding & polishing origional gelcoat is the best option all round but sometimes its just too far gone to get a good finish then painting is the easy option

[Oliver_ribfan]

Thanks for the comments, the specs are much more clear to me now.

Google threw out that it should be possible to spray topcoat/flowcoat by using a bigger nozzle. The data sheet of the topcoat that I used for the deck recommends brush or roller though.

As of today - comparing brush and spray gun - I tend to prefer the brush or roller method. With the spray gun you have the time intense prep work and with the brush you have the huge effort with the refinish afterwards. So either way you end up sanding and polishing.

Am I missing something?

[beamishken]

Originally Posted by Oliver_ribfan

Thanks for the comments, the specs are much more clear to me now.

Google threw out that it should be possible to spray topcoat/flowcoat by using a bigger nozzle. The data sheet of the topcoat that I used for the deck recommends brush or roller though.

As of today - comparing brush and spray gun - I tend to prefer the brush or roller method. With the spray gun you have the time intense prep work and with the brush you have the huge effort with the refinish afterwards. So either way you end up sanding and polishing.

Am I missing something?

Believe me there is way more work in getting gel coat to look right than there is getting a good paint finish. If you dont want to spray I'd look at one of the marine paints like international perfection pro which gives good results with a roller, far easier than gel coat but very expensive, takes ages to fully cure (weeks) & cant be polished afterwards. If you have somewhere to work & the gear with a little practice spraying with an automotive two pack is by far the best option its cheap relatively easy to use & easy to rework if you have any faults or need repairs later on

[Oliver_ribfan]

Thanks for sharing your expertise!